Using session templates in Pro Tools is a great way to speed up your workflow when creating a sessions. It lets you get to creating music faster and less time setting up tracks and plugins. When you create a session through a session template, it will contain all the internal settings of the session its created from. This includes tracks layout, tempo, audio, midi, I/O settings, buss and insert settings, plugins, etc. This can have a lot of advantages when using vi's with aux output stems, various templates for songwriting, or even when live tracking with a band.
In this Video Neil shows how incredibly useful "Track Presets" can be for using multi channel Virtual Instruments with Pro Tools as well as for simpler tasks such as effects channels.